Image Quality Assessment Techniques Using Gabor Filters

Image Quality Assessment Techniques Using Gabor Filters A SURVEY ON IMAGE QUALITY ASSESSMENT TECHNIQUES USING GABOR FILTERS Deepa Maria Thomas, S. John Livingson (DEEPA MARIA THOMAS, ROOM NO 303, DMR RESIDENCE, KARUNYA LADIES HOSTEL, KARUNYA UNIVERSITY, COIMBATORE-641114) Abstract-Image quality assessment has a very important role, especially because the impact that the quality of images have on a viewer is significant. This makes it important that visual information is assessed for quality every now and then. Images can be distorted with different types of irregularities like noise, blur etc. No- reference image quality assessment methods does not need a reference image for assessment, this is particularly helpful when there is no reference image available. Gabor filters are efficient is assessing image quality because their frequency and orientation representations is very similar to the human visual system. This is why Gabor filters are used in feature extraction , target detection as well as texture segmentation. This paper is a survey of some of the no- reference image quality assessment methods that make use of Gabor filters in their quality assessment methodology wither for feature extraction or texture analysis. Key wordsimage quality assessment, Gabor filter, no reference quality assessment. INTRODUCTION Images of good quality have come to be of great importance in our day to day life. Statistics suggest that an average person comes across 400 to 600 advertisements in a day. Pictures form a major portion of advertisements. Advertisement is just one area that makes use of images. There are a lot of image quality assessment techniques available today. No-reference image quality assessment (NR-IQA) is one of the types in which the quality is estimated without the use of any reference image, whereas full reference image quality assessment (FR-IQA) make use of a reference image for quality assessment. Gabor filter is generally used for edge detection and it has the advantage that the frequency and orientation representations are very similar to the human visual system. Or in other words, the image analysis by Gabor functions is similar to the human perception. A set of Gabor filters with different frequencies and orientations are also useful for extracting useful features from an image. GABOR FILTERS IN FEATURE EXTRACTION Use of Gabor filter is motivated by the fact that they are optimal in time and frequency. In addition these filters can approximate the visual cortex of some mammals as described in [1]. This is why Gabor filters are used in many applications like target detection, image segmentation etc.. Figure 1: Two dimensional Gabor filter Sources: http://en.wikipedia.org/wiki/Gabor_filter NR-IQA USING GABOR FILTERS No-reference image quality assessment is one of the types in which the quality is estimated without the use of any reference image, whereas full- reference techniques make use of a reference image for quality assessment. Described below are two no- reference image quality assessment techniques using Gabor filters. NR-IQA USING VISUAL CODEBOOK (CBIQ) The first step of this method [2] is codebook construction. It is built by dividing an image into BxB patches. All the constant patches are removed, for the rest of the patches Gabor feature vectors are computed. This is repeated for all the training images. Using this set, with a clustering algorithm the codebook is created. The input image is represented by the distribution of codewords from the codebook. The number of times the codeword is found and each time a nearest neighbor is found, the count is increased by one. If the distance between the vector of the feature and the nearest neighbor is larger than a predefined threshold, then it is considered as an outlier. In a case where a large number of outliers are encountered, then there might be some type of distortion which was not encountered in the training set. This image quality assessment technique is represented as CBIQ (Codebook Image Quality).The quality metric is Qm(I) and is given by, Qm(I)= where, H1(i) is the probability of the occurrence of the code words DMOS(C(i)) is the Differential Mean Opinion Scores of the codewords. NR-IQA BASED ON VISUAL SALIENCY GUIDED SAMPLING (IQVG) This method [3] is a no-reference image quality assessment method based on visual saliency. Visual saliency is what grabs our attention and it makes some parts of the image stand out from the rest. In this method firstly, a sufficient number of patches are sampled for which the mean saliency is greater than the threshold. Next, feature extraction is done by convolving each patch with Gabor filters. Using histograms the features are encoded, this gives an image representation. Using regression methods such as SVR the model can be trained. Finally, the quality of the test image is predicted automatically with a trained model. FR-IQA USING GABOR FILTERS The full reference method of image quality assessment is different from the no reference methods in that it does not make use of a reference image for quality assessment. Described below are two full reference image quality assessment techniques using Gabor filters. FR-IQA USING FEATURE SIMILARITY INDEX (FSIM) In this method [4] firstly, two image extractions are made namely, phase congruence (PC) and gradient magnitude (GM). PC is contrast invariant, this implies that the variations in quality due to contrast differences are not identified by PC. As a result of this, the GM needs to be extracted using gradient operators like Prewitt operator, Sobel operator and Scharr operator. Once the PC and GM are extracted for the reference image and the distorted image, FSIM can be computed to measure the similarity between the two images. The FSM can be calculated by combining similarity measure between images for both PC and GM given by where, is the similarity measurement of PC is the similarity measurement of GM and are positive real numbers The combined similarity is given by = . where, ÃŽ ± and ÃŽ ² are parameters to adjust their relative weightage or importance. Finally, the FSIM measure is given as below FSIM= where, FR-IQA USING PERCEPTUAL METHOD (MIGF) One of the features necessary for good IQA is that it should be consistent with the subjective judgment of humans on the image. In this method [5] first, the features are extracted using a two dimensional Gabor filter which acts as a local band-pass filter with optimal localization properties. Next, divisive normalization transform (DNTF) is performed where the linear transform coefficient is normalized by the energy of a cluster of neighboring coefficients. This reduces the higher order dependencies in the extracted Gabor features. Next, the visual energy information (VEI) for each scale and orientation is given by where, ÃŽ » is the scale, ÃŽ ¸ is the orientation is real part of DNTF is the imaginary part of DNTF Once the VEI is calculated, the mutual information (MI) can be calculated as the difference between the VEI obtained from the reference image and distorted image. MI can be calculated using marginal probability distribution and joint probability distribution. The quality score is as described below Score= where, and denote the VEI of the reference image and distorted image respectively at scale i and orientation ÃŽ ¸. COMPARISON OF IQA TECHNIQUES: The table below shows a comparison between the four techniques described above. It describes the merits and demerits of the four IQA methods. TABLE – 1 COMPARISON TABLE CONCLUSIONS This work provides the comparative study of some of the IQA methods in image processing. The algorithms that were considered were both no – reference and full reference algorithms. All the IQA methods discussed here make use of Gabor filters in one way or another. This paper highlights importance of Gabor Filters in image quality assessment. REFERENCES: [1] Anjali G. (2012), â€Å"For image enhancement and segmentation by using evaluation of Gabor filter parameters.† IJATER, 2, 46-56. [2] Peng Y. and David D. (2014), â€Å"No- reference image quality assessment based on visual codebook.† Feature Similarity Index for Image Quality Assessment.† IEEE Trans. IP, 21, 3129-3138. [3] Zhongyi G., Lin Z. and Hongyu L., (2013),â€Å"Learning a bling image quality index based on visual saliency guided sampling and Gabor filtering.† ICIP, 186-190. [4] Lin Z. and Xuanqin M., (2011), â€Å"FSIM: Feature Similarity Index for Image Quality Assessment .† IEEE Trans. IP, 20, 2378-2386 [5] Ding Y., Zhang Y., Wang X., Yan X. and Krylov A.S. (2014), â€Å"Perceptual image quality metric using mutual information of Gabor features.† Science China Information Sciences, 57,032111:1-032111:9.

Plight of African Americans Essay

African Americans plight throughout U. S. history begin as early in the 1400-s and ending in the 1700-s. In 1863 President Abraham Lincoln freed slaves in the southern states through the Emancipation Proclamation. African Americans endured many hardships such as not having rights to vote, social inequalities of African Americans were violated, equal social status, social classes, and social circles. Examples of these violation are freedom of speech, property rights, access to health care, education, and transportation. Cultural concerns of African Americans currently include not being acknowledged in most educational settings and lack of our cultural experiences in classroom settings denying African American children the right to know the history of where our ancestry evolved. All of these experiences are and some continue to be the journey of African Americans today Groups and organizations promoting racial equality are the National Association of Advancement for Colored People{NAACP}, Southern Christian Leadership Conference{SCLC}, The National Urban League, Rainbow/Push Coalition each helped paved the way for equality of races and continue to do so. Objectives of these groups was to eliminate discrimination along with racial discrimination among citizens of the United States, eliminatin barriers of discrimination through democratic processes, seek enactment and enforcement of federal, state and local laws securing civil rights to inform the public of the changes of racial discrimination and educate persons of their constitutional rights and to take lawful action to secure the exercise thereof and to take any other action in furtherance of these objectives. Experiences of the NAACP help to dismantle Jim Crow Laws, the NAACP had it’s first victory in Guinn and Beale vs. US Supreme Court this case declared it unconstitutional the â€Å"grandfather clause† in the Oklahoma Constituition which stopped voting qualifications if the individual grandfather had voted, this was an attempt by Whites to stop African Americans whose grandfathers that had been slaves. Laws and amendments were designed to constrain the racial inequalities within prejudicial boundaries such as the 13th, 14th , and 15th amendments. These amendments address unfair treatment of African Americans, amendment 13th abolished slavery, amendment 14th secured rights of slaves and equal protection under the law to all persons and helped to dismantle segregation{Brown vs. Board of Education}. Various groups, organization and people played a tremendous role in fighting for racial equality leaders like Martin Luther King, Rosa Parks, Malcolm X, Thurgood Marshall and organizations such as NAACP, SCLC, and The Urban League. These groups of people and organizations help to fight legislation through landmark court cases, peaceful and nonviolent demonstrations, protests and sit ins and with the amendments listed above. The 14th amendment contains the equal protection clause and this clause was included to protect slaves from unfair treatment, In Brown versus the Board of Education this case helped declared separate public schools for Blacks and Whites was unconstitutional as a result of dejure segregation, this is ruled a violation of the 14th amendment. Infamous boycotts and sit-ins, contributed to this fight, like The Montgomery Boycott and The Greensboro Sit In. Peaceful demonstrations in a nonviolent manner was the objectives of these organizations and leaders. Protesting for racial dignity, economic and political self sufficiency and freedom from oppression of White Americans was the goals of these leaders and organizations to help fight legislation. Several laws have been enacted to help eliminate prejudicial boundaries, these laws are often called antidiscrimination acts which addressed racial, political and social inequalities of African Americans, The Civil Right Acts of 1968,1964 and 1948, helped to outlaw major forms of discrimination against racial, ethnic, national and religious minorities and women. These acts ended unequal voter requirements, racial segregation in school, workplaces and by facilties that served the general public. These are a few of the struggles of African Americans and their journey throughout U. S. history there have been enormous strides in gaining equality for races, politically and socially, although political challenges currently face African Americans now we continue to fight for this right our ancestors have marched, died , were abused physically and verbally, remains the plight before us.

Why Almost Everything Youve Learned About Research Paper Thesis Statement Is Wrong and What You Should Know

Why Almost Everything You've Learned About Research Paper Thesis Statement Is Wrong and What You Should Know If you're writing a research paper, you have probably already taken a great deal of notes and organized the information that you have found. Ideal research paper topic is one which can be backed up with sufficient evidence. Do not pick a research paper topic that is quite tough to research about. In research, you have to do independent research. Show that you see that the research question isn't as easy as it looks. If you're well versed with the topic writing a fantastic research paper is going to be a cake walk for you. Such a topic may entail a topic that's too wide or a topic in an area where studies are conducted exhaustively. An intricate research paper topic will not simply take lot of time but in addition might not be easily comprehensible due to its complexity. 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Therefore, it requires profound research as a way to be considered trustworthy. If you should devise an analytical research, fo cus on the details you will examine to better understand the entire concept. Research Paper Thesis Statement Options Writing College research papers College courses demand various types of writing that employ a number of strategies for various audiences. Finest college research paper topics are those that are original. Pick a college research paper topic which you are acquainted with or like research on. Research is an integral component of any college program. The Argument About Research Paper Thesis Statement You could equally argue they don't have any effect, or they are harmful. Therefore, it's an important portion of any research paper. For instance, you may have made a decision to compose a paper about gambling addiction. What to Do About Research Paper Thesis Statement Before You Miss Your Chance Scholars are usually in a dilemma in regard to what constitutes a top superior management research paper. Research paper assessors love ideas which provide something new or explore a novel and advanced notion. Making up a strong statement for a research work could possibly be a daunting job. Quite simply, the thesis has to be something that different men and women could reasonably have different opinions on. Research Paper Thesis Statement Help! For example, if you're writing an analytical essay about science, you might make an extremely straightforward and clear linear argument in the shape of a single sentence. Knowing what it is that you are attempting to achieve, and committing it to paper, can be hard. The job of a thesis is to demonstrate your explanation explains words or deeds that weren't explained before. 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Prejudice and Discrimination Essay example - 1193 Words

Unfortunately due to our past history, discrimination had been among us from since decades. Discrimination and prejudice would probably be among us until the end of the world. Prejudice and discrimination is an action that treats people unfairly because of their membership in a particular social group, class, or category to which that person or thing belongs to rather on that individual. It is an unfair treatment to a person, racial group, and minority. It is an action based on prejudice. In this paper I will discuss what happens when we allow biases and prejudice to affect our actions toward others. I will then conclude my paper with what we can do to prevent or eliminate discrimination. Prejudice and discrimination push people apart†¦show more content†¦It was uncalled for and not necessary. There are so many serious issues like poverty, disease, war and so much more happening in this world. Life is already difficult therefore, why must we allow something like discrimination makes people afraid of whom they truly are. It is clear that discrimination is a part of a systematic use of power that â€Å"the enslavement of Africans in the United States, the official domination of Blacks by Whites in South Africa, and Hitlers widespread extermination of Jews are some historic examples of systematic, legal discrimination† so why can’t we break this chain. Like I mentioned in my introduction, discrimination is an action people have come to witness but yet, we still discriminate against each other. Everyone wants to be superior over the other, others on the other hand, would never accept different types of races in their mist therefore, and we will never find peace. We say America is the land of opportunity, yet immigrants and different races are not always well-treated when they come to the U.S. if you are born black, Latino, Asian, and Indian, as a citizen of an America, still limits your status in where you stand in this society. Throughout history, the most recent immigrants to this country have always confronted some sort of discrimination. They have to take the hardest, worst paid jobs, and have difficultyShow MoreRelatedDiscrimination And Prejudice And Discrimination1638 Words   |  7 PagesDiscrimination comes in a number of forms. We have age discrimination, employment or job discrimination, racial discrimination, gender discrimination, reverse discrimination, sexual discrimination, and others. Prejudice is a negative attitude toward a socially defined group and toward any person perceived to be a member of that group (Burgess, 2003). 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A person can have prejudice without acting in a discriminatory manner; however, if someone is discriminating against someone, they have prejudices. A prejudice can start from a stereotype andRead MorePrejudice and Discrimination1551 Words   |  7 PagesAnalytical Factsheet on Prejudice amp; Discrimination on Class Inequality Section 1: Executive Summary This essay is about prejudice and discrimination occurring in Singapore context to address Class discrimination. This essay will also show reasons to why prejudice and discrimination occurs and the effects of such inequity can cause to the society. In this case studies possible measures and solutions will be highlighted and suggested. 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